This agreement covers statistical work to be done by the U.S. Census Bureau for the National Institute on Alcohol Abuse and Alcoholism (NIAAA) on the National Epidemiologic Survey of Alcohol and Related Conditions (NESARC). The NESARC is the largest and most comprehensive national survey conducted on patterns of alcohol use, alcohol use disorders and co-occurring mental and physical disabilities. It was designed to be a longitudinal survey with its first wave fielded in 2001-2002 (n= 43,093), and the second wave fielded in 2004-2005 using the same respondents. The NESARC sample represents the civilian, non-institutionalized adult population of the United States, including all 50 states and the District of Columbia. It includes persons living in households, military personnel living off-base, and residents of boarding or rooming houses, non-transient hotels and motels, shelters, college quarters, and group homes. The Census Supplementary Survey, in combination with the Census 2000 Group Quarters Inventory, comprised the sampling frame for the NESARC waves one and two. The NESARC over-sampled African-Americans, Hispanics, and adults 18-24 years of age, to ensure adequate sample size for subgroup comparisons within these high-risk populations.